LAMBERTON - Soybean rust could become the next big plant pest facing southwestern Minnesota's soybean crop. Marty Draper of the South Dakota State University Extension Service, who has seen soybean rust in other countries, discussed what might need to be done to contain soybean rust as part of the Summer Field Day at the Southwest Research and Outreach Center near Lamberton. He said soybean rust is likely to spread into the U.S. in much the same way that it recently spread to South America. "It's the plant disease that’s being talked about, one that's viewed as a threat," Draper said. "The way to approach it should be to treat it as just another problem that we'll need to manage."

He said one of the advantages for Minnesota and other northern states is that soybean rust doesn't survive over the winter in cold climates. It will have to be carried in by winds every year from the South. Another factor that could help soybean growers is early detection. Draper said rust typically affects the lower part of the soybean canopy first. It will have to be monitored as the first confirmed cases show up in local areas. "We have the advantage of being able to track the disease," he said. "We'll know when it's coming. The first thing is to recognize it. It can't be treated unless it's recognized."

He said all major commercial varieties of soybeans are susceptible to soybean rust. So far there's been no field-based or genetic way to control it. Fungicide treatment at timely stages of the growing season has been important in other countries. The fungicide treatments need to be structured in ways that are compatible with existing herbicide treatment plans. Draper said a focus of soybean rust treatment has been to control its impact on soybean leaves and to prevent rust conditions from causing a substantial yield loss. "There's no known way to completely eliminate it," Draper said. "One of the things treatment options could do is slow down the symptoms."